This invention relates to mobile fluid sprayer systems, and more particularly to improvements relating to the mounting of the sprayer booms of such systems which substantially extend the working life thereof.
Mobile fluid sprayer systems are utilized in agriculture and related industries to perform a wide variety of functions. For example, mobile fluid sprayer systems are utilized in the application of fertilizers and related products. Conversely, such systems are frequently utilized in the application of herbicides such as weed killers. Mobile fluid sprayer systems may also be utilized to spray insecticides and various other fluids.
Mobile fluid sprayer systems offer significant advantages in the application of these materials. Perhaps most significantly, the materials are applied very rapidly. Also the materials can typically be applied utilizing only one operator. For these and other reasons the use of mobile fluid sprayer systems to apply fluid materials has been found to be very economical.
However, all of the mobile fluid sprayer systems which are presently available for agricultural and related uses also involve at least one significant disadvantage. This relates to the fact that most mobile fluid sprayer systems involve laterally extending booms which are liable to come into engagement with obstructions such as fenceposts, trees, and the like. This usually results in damage to the sprayer system which in turn causes down time, and may necessitate expensive repairs.
Another problem common to most prior art mobile fluid sprayer systems involves the fact that the laterally extending booms thereof are typically either rigidly secured, or are at least very heavy and stiff structures. Because of this the vibration and shock loads that are encountered when mobile fluid sprayer systems are operated over rough terrain cause the boom structures to self-destruct even though they do not come into engagement with any kind of an obstruction. This factor requires the operation of many prior art mobile fluid sprayer systems at substantially reduced speeds in order to maintain the vibration and shock loads that are imposed on the boom structures within acceptable limits.
Attempts have heretofore been made to overcome these problems. One approach has been to provide for pivotal movement of the sprayer boom structure upon engagement with obstructions. It has been found, however, that even this approach does not provide wholly satisfactory results. For example, after the obstruction has been cleared, the sprayer boom may tend to return to its normal position very rapidly resulting in high shock loads, vibrations, and similar problems.
The present invention comprises a mobile fluid spayer system which overcomes the foregoing and other disadvantages long since associated with prior art. In accordance with the broader aspects of the invention, a mobile fluid sprayer system includes at least one generally laterally extending sprayer boom comprising a relatively light, floatingly supported structure. Structure is provided for permitting the boom to freely pivot both upwardly and rearwardly upon engagement of the sprayer boom with an obstruction. The return movement of the sprayer boom to the normal position is substantially damped, whereby the sprayer boom clears the obstruction without damage either due to contact between the boom and the obstruction or due to the return movement of the boom to the normal position. Moreover, the motion of the boom is constantly damped, and the damping rate is graduated, with maximum damping when the boom is at or near the normal position and with reduced damping as the boom is pivoted away from the normal position. This is highly beneficial from at least two standpoints. First, the boom is allowed to return very rapidly from a pivoted position to the normal position, but no significant shock or vibration loads are imposed on the boom due to the rapid return movement. Second, this feature of the invention allows the mobile fluid sprayer system to be operated at relatively high speeds over rough terrain without imposing significant shock or vibration loads on the boom.
In accordance with more specific aspects of the invention, fluid cylinder apparatus is employed in damping the return movement of the sprayer boom to the normal position. Two fluid cylinder apparatus are preferably utilized. Although both fluid cylinder apparatus function to damp both vertical and horizontal boom movement, the first fluid cylinder apparatus serves primarily to damp return motion of the boom in the vertical direction and the second fluid cylinder apparatus serves primarily to damp the return motion of the sprayer boom in the horizontal direction. In this manner the correct amount of damping in both directions is provided.
The sprayer boom extends generally laterally from a vehicle and is normally positioned by a pair of cables extending angularly upwardly from the boom. The cables are connected at points located forwardly and rearwardly from the boom on a bracket which is pivotally supported on the vehicle. The bracket is spring biased upwardly, and the first fluid cylinder apparatus is utilized to damp both upward and downward pivotal movement of the bracket. In this manner the bracket tracks the boom upwardly and return pivotal movement of the sprayer boom in the vertical direction is substantially damped.
Two embodiments of the second fluid cylinder apparatus are disclosed. In one embodiment a fluid cylinder is coupled to the sprayer boom by means of a Bowden wire, and springs are employed to cause the fluid cylinder to follow the motion of the sprayer boom during rearward pivotal movment thereof. The return pivotal movement of the boom is thereafter damped by the fluid cylinder operating through the Bowden wire.
In the second embodiment a cam is secured to the sprayer boom and the fluid cylinder extends to a cam follower. Structure is provided for rapidly advancing the fluid cylinder during rearward pivotal movement of the sprayer boom. The return movement of the fluid cylinder is substantially restricted, thereby providing substantial damping of the return of the sprayer boom to the normal position.